An experienced circuit designer generally recognizes that the task of designing an efficient power supply circuit requires that the issues of current measurement and current control be considered. One of the most important reasons for applying an over temperature protection circuit to a power supply circuit is that a current limit or over-load protection can be provided for the power supply circuit.
In a conventional circuit, the over temperature protection circuit comprises an overload measuring member and a temperature measuring member. In this solution, it is disadvantageous that comparatively many components are required since an overload and an over temperature are identified by different measuring members, that is, by the overload and the temperature measuring members. Such an over temperature protection circuit occupies a large volume.